Answer:
Explanation:
When the positively charged half shell is brought in contact with the electroscope, its needle deflects due to charge present on the shell.
When the negatively charged half shell is brought in contact with the positively charged shell , the positive and negative charge present on each shell neutralises each other .So both the shells lose their charges .The positive half shell also loses all its charges
When we separate the half shells , there will be no deflection in the electroscope because both the shell have already lost their charges and they have become neutral bodies . So they will not be able to produce any deflection in the electroscope.
These are the Kepler's laws of planetary motion.
This law relates a planet's orbital period and its average distance to the Sun. - Third law of Kepler.
The orbits of planets are ellipses with the Sun at one focus. - First law of Kepler.
The speed of a planet varies, such that a planet sweeps out an equal area in equal time frames. - Second law of Kepler.
Answer:
<em>The work done by the car is 363 kJ</em>
Explanation:
Work : Work is said to be done when a Force moves an object through a certain distance. Work and Energy are interchangeable because they have the same unit. The unit of work is Joules (J).
Mathematically work done can be expressed as,
E = W = 1/2mv²
W = 1/2mv²................................ Equation 1
Where E = Energy, W = work done, m = mass of the car, v = velocity of the car
<em>Given: m=1500 kg, v=22 m/s</em>
<em>Substituting these values into equation 1</em>
<em>W = 1/2(1500)(22)²</em>
<em>W = 750 × 484</em>
<em>W = 363000 J</em>
<em>W = 363 kJ</em>
<em>Thus the work done by the car is 363 kJ</em>
Answer:
C. Fill two identical pots with equal volumes of salt water and tap water and use a stopwatch to determine the time it takes each pot to boil.
Explanation:
<u>A) is incorrect</u> because Peter should have the same testing environment for both of his experiments.
He should choose the same method of boiling the salt water and tap water because the stovetop and the microwave could also affect the results and make them unreliable.
<u>B) is incorrect</u> because Peter should not estimate the time it takes the salt water and tap water to boil.
Peter should measure and record the amount of time that it takes these substances to boil in order to have an accurate, valid experimental thesis.
<u>C) is correct</u> because Peter uses the same volume of salt water and tap water, fills them into two identical pots, and uses a stopwatch to determine the amount of time it takes each pot to boil.
The stopwatch makes the experiment more valid and accurate compared to the previous methods, and the identical pots and amounts of water help this experiment become even more precise.
<u>D) is incorrect</u> because the variables in the experiment are not controlled amounts and will therefore produce an inaccurate and invalid experiment.
